Java中的DecimalFormat用法解析

double pi = 13.1415926;
System.out.println(new DecimalFormat("整数部分是#").format(pi));//13
System.out.println(new DecimalFormat("0.0").format(pi));//13.1
System.out.println(new DecimalFormat("000.000").format(pi));//013.142
//以百分比方式计数，并取两位小数
System.out.println(new DecimalFormat("#.##%").format(pi));//1314.16%
System.out.println(DecimalFormat.getCurrencyInstance().format(pi));//￥13.14
long c=299792458;//光速
//每三位以逗号进行分隔
System.out.println(new DecimalFormat(",###").format(c));//299,792,458

System.out.println(new java.text.DecimalFormat("#.###").format(3.0));  //3
System.out.println(new java.text.DecimalFormat("0.000").format(3.0) ); //3..000
DecimalFormat df1,df2;

System.out.println("整数部分0/#的区别");

df1 = new DecimalFormat("#.00");
df2 = new DecimalFormat("0.00");

System.out.println(df1.format(0.1)); // .10
System.out.println(df2.format(0.1)); // 0.10  

System.out.println("小数部分0/#的区别");

df1 = new DecimalFormat("0.00");
df2 = new DecimalFormat("0.##");

System.out.println(df1.format(0.1)); // 0.10
System.out.println(df2.format(0.1)); // 0.1

System.out.println(df1.format(0.006)); // 0.01
System.out.println(df2.format(0.006)); // 0.01

System.out.println("3、整数部分有多位");

df1 = new DecimalFormat("0.00");
df2 = new DecimalFormat("#.00");

System.out.println(df1.format(2)); // 2.00
System.out.println(df2.format(2)); // 2.00

System.out.println(df1.format(20)); // 20.00
System.out.println(df2.format(20)); // 20.00

System.out.println(df1.format(200)); // 200.00
System.out.println(df2.format(200)); // 200.00